[ROOT] TGeoMCGeometry vs. TGeoManager

From: Peter Steinberg (peter.steinberg@bnl.gov)
Date: Tue Apr 13 2004 - 23:06:43 MEST

Hi everyone (esp. the VMC team) -

I'm trying to use the geant3 module in ROOT 4-00-03 but am
having trouble incorporating my own geometry into the examples.

I've already defined a geometry using the TGeoManager class
and saved it to a file.  I've then hacked in my geometry into
the E01 example in geant4_vmc, by reading it in from a file
(using TGeoManager::Import), but when i run the example i get
this output:


  MZLINK.  Initialize Link Area  /GCSLNK/  for Store  0 NL/NS=   100   100
Geant3 has been created.
Geometry will be defined via TGeo
===> TGeo, Root geometry manager created
Warning in <TGeoManager::dtor>: deleting previous geometry: TGeo/Root 
geometry manager
===> ,  created
### Geometry loaded from file...
Top volume is TOP. Master volume is TOP
### Voxelization retrieved from file
--- node ID tracking disabled
### 195 nodes/ 18 volume UID's in Simple geometry
----------------modeler ready----------------

  Calculating cross section tables, see gphysi.dat for more information

  Cross section calculation concluded successfully
  **** GTRIGI: IEVENT=      1 IDEVT=      1 Random Seeds =          0 
root [1]


i.e. it doesn't crash, but nothing happens!  this example works fine
in its original form, so it's really just the introduction of my

my main suspicion is that i really should be using the TGeoMCGeometry
interface from the beginning, but if i check the source, i see that
the MCGeometry is using the GeoManager anyway.

so my question is if i really have to rewrite my geometry using
the TGeoMCGeometry interface, or if there is a way to "import" an
existing TGeoManager into the TGeoMCGeometry -- or if I am completely
misunderstanding something!


Dr. Peter Steinberg

Associate Scientist                       Brookhaven National Laboratory
Office: +1 631-344-4390                  t-Mobile (SMS): +1 917-443-7417
Email: peter.steinberg@bnl.gov    Web: http://www.rhic.bnl.gov/~steinber

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